Rewrite detection system, rewrite detection device and information processing device

ABSTRACT

A rewrite detection system, a rewrite detection device and an information processing device can detect unauthorized rewrite to a program or data stored in a storage unit of the information processing device. A rewrite detection device generates a random seed and transmits it to an ECU and a server device. The ECU calculates a hash value using a predetermined hash function on the basis of the received random seed and the storage content of the storage unit, and transmits the hash value to the rewrite detection device. The server device transmits an expectation in response to an inquiry from the rewrite detection device. The rewrite detection device determines whether unauthorized rewrite to a program or data in the ECU has been performed or not in accordance with whether the expectation received from the server device and the hash value received from the ECU coincide with each other or not.

TECHNICAL FIELD

The present invention relates to: a rewrite detection system, whichdetects unauthorized rewrite to a program or data in an informationprocessing device such as an ECU (Electronic Control Unit) mounted on avehicle; a rewrite detection device and an information processingdevice, which act as a component of the system.

BACKGROUND ART

In an information processing device such as an ECU mounted on a vehicle,a processing unit such as a CPU (Central Processing Unit) performsvarious processing on the basis of a program and data stored in astorage unit such as a ROM (Read Only Memory). In recent vehicles, afunction is put into practical use to rewrite a program or data storedin a storage unit of an information processing device via an in-vehiclenetwork such as a CAN (Controller Area Network). This facilitatesversion upgrading or the like of software in an information processingdevice, and facilitates implement of functionalization of theinformation processing device.

Patent Document 1 proposes an onboard network system provided with aconfiguration management device for authenticating an onboard controldevice, the configuration management device being configured todistribute configuration certification data to be used for configurationcertification to an onboard control device via a registration deviceconnected with an onboard network.

CITATION LIST Patent Document

[Patent Document 1] Japanese Patent Application Laid-Open No. 2013-17140

SUMMARY OF INVENTION Technical Problems

In a configuration wherein a program and data stored in a storage unitof an information processing device are rewritable, unauthorized rewriteto the program and data may possibly be performed. For example, when anunspecified large number of users utilize a vehicle by car sharing, carrental or the like, a malicious user may possibly perform unauthorizedrewrite. Moreover, for example, a user can illegally modify his ownvehicle.

An idea to prevent unauthorized rewrite to a program or data in astorage unit is to mount a high-level authentication function, anencryption function or the like on an information processing device, forexample. However, mounting such a function on an information processingdevice has a problem of causing a cost increase of the informationprocessing device. Moreover, it is not easy to completely preventunauthorized rewrite. The onboard network system described in PatentDocument 1 also has a similar problem.

The present invention has been made in view of such a situation, and anobject thereof is to provide a rewrite detection system, a rewritedetection device and an information processing device, which can detectunauthorized rewrite to a program or data stored in a storage unit ofthe information processing device.

Solution to Problems

A rewrite detection system according to the present invention is arewrite detection system for checking an information processing device,which has a storage unit for storing a program or data, a processingunit for performing processing based on a program or data stored in thestorage unit, and a communication unit for communicating with anotherdevice via a network, so as to detect rewrite to a program or datastored in the storage unit, characterized by comprising a rewritedetection device, which has: seed information transmission means fortransmitting seed information to the information processing device viathe network; hash value reception means for receiving a hash valuetransmitted from the information processing device in response to seedinformation transmitted by the seed information transmission means; andhash value determination means for determining whether a hash valuereceived by the hash value reception means is valid or not, and detectsrewrite in accordance with a result of determination by the hash valuedetermination means, wherein the information processing device has hashvalue calculation means for calculating a hash value based on seedinformation transmitted by the seed information transmission means and aprogram or data stored in the storage unit, and is configured totransmit a hash value calculated by the hash value calculation means tothe rewrite detection device.

Moreover, the rewrite detection system according to the presentinvention is characterized in that the seed information transmissionmeans of the rewrite detection device transmits storage areaspecification information, which specifies a storage area in the storageunit, to the information processing device together with the seedinformation, and the hash value calculation means of the informationprocessing device is configured to calculate a hash value on the basisof the seed information and a program or data stored in a storage areain the storage unit, which is specified by the storage areaspecification information transmitted together with the seedinformation.

Moreover, the rewrite detection system according to the presentinvention is characterized in that the seed information transmissionmeans is configured to transmit the storage area specificationinformation including information which specifies a head position of astorage area, and a tail position or a size of the storage area.

Moreover, the rewrite detection system according to the presentinvention is characterized in that a plurality of discontinuous areascan be specified as the storage area, and the seed informationtransmission means is configured to transmit the storage areaspecification information including information which specifies theplurality of areas.

Moreover, the rewrite detection system according to the presentinvention is characterized in that the storage area specificationinformation is information which specifies an interval between theplurality of areas.

Moreover, the rewrite detection system according to the presentinvention is characterized in that the information processing device isconfigured not to transmit a hash value to the rewrite detection devicewhen specification of a storage area by the storage area specificationinformation received together with the seed information does not satisfya predetermined condition.

Moreover, the rewrite detection system according to the presentinvention is characterized in that the information processing device isconfigured not to transmit a hash value to the rewrite detection devicewhen a size of a storage area specified by the storage areaspecification information is neither a predetermined size nor a size ofa constant multiple of the predetermined size.

Moreover, the rewrite detection system according to the presentinvention is characterized in that the information processing devicedecides a storage area in the storage unit to be an object of hash valuecalculation on the basis of seed information transmitted by the seedinformation transmission means, and the hash value calculation means isconfigured to calculate a hash value on the basis of a program or datastored in the storage area decided on the basis of seed information.

Moreover, the rewrite detection system according to the presentinvention is characterized in that the information processing device isconfigured not to transmit a hash value until a predetermined period oftime elapses after transmitting a hash value to the rewrite detectiondevice.

Moreover, the rewrite detection system according to the presentinvention is characterized in that the storage unit stores random datain a surplus area other than a storage area where the program or data isstored.

Moreover, the rewrite detection system according to the presentinvention is characterized in that the rewrite detection device hasmeasurement means for measuring a period of time from transmission ofseed information by the seed information transmission means to receptionof a hash value by the hash value reception means, and is configured todetect rewrite in accordance with a period of time measured by themeasurement means.

Moreover, the rewrite detection system according to the presentinvention is characterized in that the seed information transmissionmeans is configured to transmit a random value as the seed information.

Moreover, the rewrite detection system according to the presentinvention is characterized by further comprising a server device havingtransmission means for transmitting an expectation of the hash value forthe seed information, wherein the rewrite detection device has: inquirymeans for making an inquiry for an expectation of the hash value for theseed information to the server device; and reception means for receivingthe expectation transmitted from the server device for the inquiry fromthe inquiry means, and the hash value determination means is configuredto determine whether a hash value received by the hash value receptionmeans is valid or not on the basis of an expectation received by thereception means.

Moreover, the rewrite detection system according to the presentinvention is characterized by further comprising a server device havingtransmission means for transmitting the seed information and anexpectation of a hash value, wherein the rewrite detection device has:inquiry means for making an inquiry for the seed information and theexpectation to the server device; and reception means for receiving theseed information and the expectation transmitted from the server devicefor the inquiry from the inquiry means, the seed informationtransmission means is configured to transmit the seed information, whichhas been received by the reception means from the server device, to theinformation processing device, and the hash value determination means isconfigured to determine whether a hash value received by the hash valuereception means is valid or not on the basis of an expectation receivedby the reception means.

Moreover, the rewrite detection system according to the presentinvention is characterized in that the rewrite detection device ismounted on a mobile body, and, when communication with the server devicecan be made, causes the inquiry means to make an inquiry, causes thereception means to receive the expectation, and stores the receivedexpectation, and the hash value determination means is configured todetermine whether a hash value received by the hash value receptionmeans is valid or not on the basis of the stored expectation.

Moreover, the rewrite detection system according to the presentinvention is characterized in that the rewrite detection device ismounted on a mobile body.

Moreover, the rewrite detection system according to the presentinvention is characterized in that the rewrite detection device isconfigured to be attachable to and detachable from the network.

Moreover, a rewrite detection device according to the present inventionis a rewrite detection device for detecting rewrite to a program or datastored in a storage unit of another device, characterized by comprising:seed information transmission means for transmitting seed information tosaid another device via a network; hash value reception means forreceiving a hash value transmitted from said another device in responseto seed information transmitted by the seed information transmissionmeans; and hash value determination means for determining whether a hashvalue received by the hash value reception means is valid or not,wherein rewrite is detected in accordance with a result of determinationby the hash value determination means.

Moreover, an information processing device according to the presentinvention is an information processing device characterized bycomprising: a storage unit for storing a program or data; a processingunit for performing processing based on a program or data stored in thestorage unit; a communication unit for communicating with another devicevia a network; and hash value calculation means for calculating a hashvalue based on seed information transmitted from another device and aprogram or data stored in the storage unit, wherein a hash valuecalculated by the hash value calculation means is transmitted to saidanother device.

In the present invention, a rewrite detection device generates seedinformation and transmits the seed information to an informationprocessing device, and the information processing device calculates ahash value on the basis of received seed information and a program ordata stored in a storage unit and transmits the hash value to therewrite detection device. As seed information, a random value having apredetermined number of bits can be generated and used, for example. Therewrite detection device determines whether a hash value received fromthe information processing device is valid or not, and determineswhether unauthorized rewrite to a program or data has been performed ornot. That is, the rewrite detection device can determine thatunauthorized rewrite has not been performed when the hash value isvalid, or can determine that unauthorized rewrite has been performedwhen the hash value is invalid.

This makes it possible to detect unauthorized rewrite to a program ordata in the information processing device, and to appropriately carryout treatment such as operation stop, repair or replacement of aninformation processing device for which unauthorized rewrite has beenperformed. Since added to the information processing device is only thefunction to calculate a hash value, it is possible to suppress a costincrease of the information processing device for implementing thesystem. This system can be implemented more easily and at a lower costthan a case where a function to prevent unauthorized rewrite is mounted.

Moreover, in the present invention, in the process of transmitting seedinformation to the information processing device, the rewrite detectiondevice transmits storage area specification information, which specifiesan area in the storage unit to be the object of hash value calculation,together. The information processing device calculates a hash value onthe basis of a program or data stored in a storage area specified by thestorage area specification information.

When many programs or much data is stored in the storage unit and thethroughput of the information processing device is low, hash valuecalculation may possibly require a long period of time in a case wherethe whole storage unit is to be processed. Therefore, by causing theinformation processing device to calculate a hash value only for a partof the storage unit, it becomes possible to shorten a period of timerequired for processing of calculating a hash value. It is to be notedthat the rewrite detection device may acquire a hash value a pluralityof times from the information processing device and determine whetherunauthorized rewrite has been performed or not while changing the objectarea of hash value calculation.

Moreover, in the present invention, the storage area specificationinformation includes information, which specifies the head position andthe tail position of the storage area, or information, which specifiesthe head position and the size of the storage area. This allows therewrite detection device to specify a part of the storage unit of theinformation processing device as a storage area to be the object of hashvalue calculation in a manner such as “from address X to address Y” or“Y bytes from address X”.

Moreover, the storage area to be the object of hash value calculation isnot necessarily one continuous area in the storage unit, but a pluralityof discontinuous areas may be specified as the storage area. In such acase, the storage area specification information can be information,which specifies the interval of a plurality of areas, for example. Thisallows the rewrite detection device to specify a plurality of storageareas in the storage unit of the information processing device as theobject area of hash value calculation in a manner such as “at addressinterval Z (or Z byte)”.

It is to be noted that it is also possible to specify a storage areausing any combination thereof in a manner such as “from address X toaddress Y at address interval Z”.

Moreover, in the present invention, the information processing devicedecides a storage area to be the object of hash value calculation on thebasis of seed information from the rewrite detection device, calculatesa hash value on the basis of the storage content of the storage area,and transmits the hash value to the rewrite detection device. Thisshortens a period of time required for calculation processing of a hashvalue by the information processing device, and also prevents increasein information to be transmitted from the rewrite detection device tothe information processing device.

In a configuration wherein a hash value can be calculated for a part ofthe storage area as described above, a malicious user or the like maypossibly specify a minute area, repeatedly acquire a hash value, andanalyze each acquired hash value, so that a program or data stored inthe storage unit is decoded.

Therefore, in the present invention, the information processing deviceis configured not to transmit a hash value when storage areaspecification information is given from the rewrite detection device andspecification of a storage area does not satisfy a predeterminedcondition. As the predetermined condition, whether the size of aspecified storage area is one of a predetermined size and a size of aconstant multiple of a predetermined size or not can be determined, forexample. This makes it difficult to decode a program or data on thebasis of a hash value, which has been acquired in an unauthorizedmanner.

Moreover, in the present invention, after a hash value is calculated onthe basis of seed information from the rewrite detection device andtransmitted to the rewrite detection device, the information processingdevice does not transmit a hash value until a predetermined period oftime elapses even when next seed information is given from the rewritedetection device. This limits the amount of hash values to be obtainedin a certain period of time, and therefore makes it difficult to acquirea hash value in an unauthorized manner and decode a program or data.

For example, unauthorized processing may possibly be performed bycompressing an authorized program or authorized data stored in thestorage unit and storing an unauthorized program or unauthorized data inan unused area (area where any program or any data is not stored) of thestorage unit to be obtained by the compression.

Therefore, in the present invention, random data is stored in a surplusarea where any program or any data is not stored in a case where anauthorized program or authorized data is stored in the storage unit.This makes it difficult to compress a program or data stored in thestorage unit.

It is to be noted that a program or data may be stored in the storageunit so that surplus areas lie scattered, and random data to be writtenin a surplus area may lie scattered in the storage unit.

In order to compress a program or data and perform unauthorizedprocessing as described above, an unauthorized program needs tocalculate a valid hash value on the basis of an authorized program orauthorized data which has been compressed in the process of calculatinga hash value in response to a request from the rewrite detection device,and such processing requires a longer period of time than normal hashvalue calculation processing.

Therefore, in the present invention, a period of time from transmissionof seed information by the rewrite detection device to reception of ahash value is measured, and the rewrite detection device determines thatunauthorized rewrite has been (or may have been) performed when themeasured period of time is longer than a preset threshold or the like.

Moreover, in the present invention, a server device stores anexpectation of a hash value for seed information, and the rewritedetection device acquires an expectation from the server device.Alternatively, a server device may store an authorized program orauthorized data, and the server device may be configured to calculate anexpectation for seed information. The rewrite detection device makes aninquiry for an expectation of a hash value for seed information, whichhas been transmitted to the information processing device, to the serverdevice, and receives an expectation transmitted from the server devicein response to the inquiry. The rewrite detection device compares theexpectation received from the server device with the hash value receivedfrom the information processing device, and can determine thatunauthorized rewrite has been performed when the values do not coincidewith each other.

For example, in a configuration wherein the rewrite detection devicestores an expectation, the stored expectation may possibly be rewrittenin an unauthorized manner. A configuration wherein the rewrite detectiondevice acquires an expectation from the server device can preventunauthorized rewrite to an expectation, and can enhance accuracy inrewrite detection of a program or data in the information processingdevice.

Moreover, the server device transmits the seed information and theexpectation to the rewrite detection device, and the rewrite detectiondevice transmits the seed information, which has been acquired from theserver device, to the information processing device. In response, theinformation processing device calculates a hash value and transmits thehash value to the rewrite detection device, and the rewrite detectiondevice may be configured to determine whether unauthorized rewrite hasbeen performed or not on the basis of the hash value from theinformation processing device and the expectation from the serverdevice.

Moreover, in the present invention, the rewrite detection device ismounted on a vehicle. For example, a gateway, a car navigation system orthe like mounted on a vehicle may have the function of the rewritedetection device. This makes it easy to increase the frequency ofdetection processing by performing detection processing of unauthorizedrewrite each time the engine of the vehicle starts, for example.

Here, when a rewrite detection device is mounted on a vehicle, therewrite detection device is not always communicable with a serverdevice. Therefore, the rewrite detection device preliminarily acquiresand stores an expectation of a hash value from the server device. In acase where the rewrite detection device is not communicable with theserver device in the process of detection processing, the rewritedetection device can perform detection processing using a storedexpectation.

Moreover, in the present invention, the rewrite detection device isconfigured to be attachable to and detachable from an in-vehiclenetwork. For example, the rewrite detection device may be a portabledevice, and can be configured to be communicable with the informationprocessing device via an in-vehicle network when being connected with aconnector of the vehicle via a cable or the like.

Such a rewrite detection device may be provided in a dealer shop, amaintenance shop or the like of a vehicle, for example, so thatunauthorized rewrite to a program or data in an information processingdevice can be detected in the process of safety inspection, periodicinspection, repair or the like of the vehicle. Moreover, in the case ofa vehicle for car rental, car sharing or the like, for example, therewrite detection device can perform unauthorized rewrite detectionafter the vehicle is returned.

Advantageous Effects of Invention

With the present invention, a rewrite detection device can detectunauthorized rewrite to a program or data stored in a storage unit of aninformation processing device.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 A schematic diagram for illustrating the configuration of arewrite detection system according to Embodiment 1.

FIG. 2 A block diagram for illustrating the configuration of an ECU.

FIG. 3 A schematic diagram for illustrating the configuration of astorage unit of an ECU.

FIG. 4 A block diagram for illustrating the configuration of a rewritedetection device.

FIG. 5 A block diagram for illustrating the configuration of a serverdevice.

FIG. 6 A schematic diagram for illustrating First Configuration Exampleof a rewrite detection database.

FIG. 7 A schematic diagram for illustrating Second Configuration Exampleof a rewrite detection database.

FIG. 8 A schematic diagram for explaining rewrite detection processingto be performed by a rewrite detection device.

FIG. 9 A flowchart for illustrating the process procedures of rewritedetection processing to be performed by a rewrite detection device.

FIG. 10 A flowchart for illustrating the process procedures of rewritedetection processing to be performed by an ECU.

FIG. 11 A flowchart for illustrating the process procedures of rewritedetection processing to be performed by a server device.

FIG. 12 A flowchart for illustrating the process procedures of rewritedetection processing to be performed by an ECU according to Embodiment2.

FIG. 13 A schematic diagram for illustrating the configuration of arewrite detection system according to Embodiment 3.

FIG. 14 A block diagram for illustrating the configuration of a gateway.

FIG. 15 A flowchart for illustrating the process procedures of rewritedetection processing to be performed by a gateway according toEmbodiment 3.

DESCRIPTION OF EMBODIMENTS Embodiment 1 System Configuration

The following description will give a specific explanation on thepresent invention with reference to the drawings for illustratingembodiments thereof. FIG. 1 is a schematic diagram for illustrating theconfiguration of a rewrite detection system according to Embodiment 1.Denoted at 1 in the drawings is a vehicle, and various ECUs 2 such as abody ECU and an engine ECU, for example, are mounted on the vehicle 1. Aplurality of ECUs 2 mounted on the vehicle 1 are connected with eachother via an in-vehicle network 3 such as a CAN so as to transmit andreceive information to and from each other. The vehicle 1 is alsoprovided with a connector 4 to be used for connecting the in-vehiclenetwork 3 with another device.

The rewrite detection system according to Embodiment 1 is provided witha rewrite detection device 5 for detecting unauthorized rewrite to aprogram or data in the ECUs 2 mounted on the vehicle 1. The rewritedetection device 5 is a portable device, and is stored in a dealer shop,a repair shop or the like of the vehicle 1, for example. The rewritedetection device 5 becomes communicable with the ECUs 2 via thein-vehicle network 3 when being connected with the connector 4 providedin the vehicle 1 via a communication cable 6. The rewrite detectiondevice 5 performs detection processing of unauthorized rewrite to aprogram or data in an ECU 2 in a state where the communication cable 6is connected with the connector 4.

The rewrite detection device 5 also has a function to make wirelesscommunication utilizing a wireless LAN (Local Area Network), a portabletelephone network or the like. The rewrite detection device 5 in thisembodiment utilizes such a wireless communication function tocommunicate with a server device 7 via a network 9 such as the Internet.The server device 7 is a device to be managed and administered by amanufacturing company, a sales company or the like of the vehicle 1, forexample. The server device 7 stores information to be used for rewritedetection processing to be performed by the rewrite detection device 5,and transmits required information to the rewrite detection device 5 inresponse to a request to be given from the rewrite detection device 5 inthe process of rewrite detection processing.

FIG. 2 is a block diagram for illustrating the configuration of an ECU2. The ECU 2 is composed of a processing unit 21, a storage unit 22, acommunication unit 23 and the like. The processing unit 21 isconstituted of an arithmetic processing unit such as a CPU (CentralProcessing Unit). The processing unit 21 reads out and executes aprogram stored in the storage unit 22 to perform various informationprocessing related to the vehicle 1.

The storage unit 22 is constituted of a nonvolatile and data-rewritablememory element such as a flash memory or an EEPROM (ElectricallyErasable Programmable Read Only Memory). The storage unit 22 stores aprogram to be executed by the processing unit 21, and various data to beused for processing to be performed by the program. In this embodiment,the storage unit 22 is used as a ROM, and a program or data stored inthe storage unit 22 shall not be rewritten in processing by theprocessing unit 21. Here, rewrite for version upgrading or the like of aprogram can be achieved.

The communication unit 23 communicates with another ECU 2 via thein-vehicle network 3 according to a communication protocol such as aCAN, for example. The communication unit 23 converts information fortransmission given from the processing unit 21 into a transmissionsignal according to a communication protocol, and outputs the signalacquired by conversion to a communication line which constitutes thein-vehicle network 3 so as to transmit the information to another ECU 2.The communication unit 23 samples the electrical potential of thecommunication line of the in-vehicle network 3 so as to acquire a signaloutputted from another ECU 2, converts the signal into binaryinformation according to a communication protocol so as to receiveinformation, and gives the received information to the processing unit21.

The processing unit 21 of the ECU 2 in this embodiment also has a hashvalue calculation unit 24 for calculating a hash value in response to aninstruction from the rewrite detection device 5. The hash valuecalculation unit 24 calculates a hash value using a predetermined hashcalculation algorithm (hash function) on the basis of a random seed(seed information) given from the rewrite detection device 5, and aprogram or data stored in the storage unit 22. The hash valuecalculation unit 24 may be implemented as software, or may beimplemented as hardware. Details of a hash value calculation method willbe described later.

FIG. 3 is a schematic diagram for illustrating the configuration of thestorage unit 22 of an ECU 2. In the illustrated example, the storageunit 22 has storage areas, each having an address from 0000h to FFFFh.The storage unit 22 stores two programs (Program 1 and Program 2) to beexecuted by the processing unit 21, and two kinds of data (Data 1 andData 2) to be respectively used for the execution of the programs. Thestorage unit 22 stores Program 1, Program 2, Data 1 and Data 2 in thisorder from the head side of the addresses, and dummy data is stored instorage areas therebetween and in a storage area on the tail side of theaddresses.

Dummy data may be any value, and a value decided randomly, for example,can be stored. Dummy data is written in all surplus areas in the storageunit 22. That is, some data is stored in the whole storage area in thestorage unit 22. This prevents unauthorized processing by storing anunauthorized program in a surplus area in the storage unit 22. This alsomakes it difficult to compress a program and data stored in the storageunit 22.

FIG. 4 is a block diagram for illustrating the configuration of therewrite detection device 5. The rewrite detection device 5 is composedof a processing unit 51, a storage unit 52, an operation unit 53, adisplay unit 54, a wired communication unit 55, a wireless communicationunit 56 and the like. The processing unit 51 is constituted of anarithmetic processing unit such as a CPU. The processing unit 51 readsout and executes a program stored in the storage unit 52 so as toperform detection processing of unauthorized rewrite to a program ordata in the ECUs 2 mounted on the vehicle 1. The storage unit 52 isconstituted of a nonvolatile memory element such as a flash memory, andstores a program to be executed by the processing unit 51, and variousdata to be used for the execution. The rewrite detection device 5 maystore temporary information, which is generated in a process stage orthe like of the processing unit 51, or may be provided with a RAM(Random Access Memory) for storing temporary information.

The operation unit 53 is constituted of a push switch, a touch panel orthe like, and accepts operation by the user and gives notice to theprocessing unit 51. The display unit 54 is constituted of a liquidcrystal panel or the like, and displays various images, messages and thelike for the user in response to an instruction from the processing unit51. The wired communication unit 55 communicates with another device viathe communication cable 6 according to a communication protocol such asa CAN, for example. When the communication cable 6 is connected with theconnector 4 of the vehicle 1, the wired communication unit 55 becomescommunicable with the ECUs 2 via the in-vehicle network 3 of the vehicle1. The wireless communication unit 56 makes wireless communicationutilizing a wireless LAN, a portable telephone network or the like, soas to communicate with the server device 7 via the network 9 such as theInternet.

FIG. 5 is a block diagram for illustrating the configuration of theserver device 7. The server device 7 is composed of a processing unit71, a storage unit 72, a communication unit 73 and the like. Theprocessing unit 71 is constituted of an arithmetic processing unit suchas a CPU. The processing unit 71 reads out and executes a program storedin the storage unit 72 so as to perform processing to transmitinformation to be used for rewrite detection processing by the rewritedetection device 5. The communication unit 73 is to communicate withanother device via the network 9 such as the Internet. The communicationunit 73 in this embodiment communicates with the rewrite detectiondevice 5, gives information received from the rewrite detection device 5to the processing unit 71, and transmits information for transmissiongiven from the processing unit 71 to the rewrite detection device 5.

The storage unit 72 is constituted of a mass storage device such as ahard disk. In this embodiment, a rewrite detection database 75 isconstructed in the storage unit 72. The rewrite detection database 75 isa database which stores information to be used for rewrite detectionprocessing by the rewrite detection device 5. The following descriptionwill illustrate two configuration examples of the rewrite detectiondatabase 75, though there are several possible configurations for therewrite detection database 75.

FIG. 6 is a schematic diagram for illustrating First ConfigurationExample of the rewrite detection database 75. In the rewrite detectiondatabase 75 of First Configuration Example, “Vehicle Model”, “ECUClass”, “Random Seed” and “Expectation” are stored in association witheach other. As “Vehicle Model” in the rewrite detection database 75,identification information or the like to be used for identifying thetype of the vehicle 1 or the like is stored. When vehicles 1 havedifferent grades and different configurations of ECUs 2 mounted thereon,the vehicles 1 are treated as different vehicle models in thisembodiment even when the vehicles 1 have the same vehicle name,appearance and the like. In the illustrated example, information such asVehicle Model A, Vehicle Model B, . . . is stored as “Vehicle Model” inthe rewrite detection database 75. As “ECU Class” in the rewritedetection database 75, identification information or the like to be usedfor identifying the type of an ECU 2 such as a body ECU or an engineECU, for example, is stored. In the illustrated example, informationsuch as ECU a, ECU b, . . . is stored as “ECU Class” in the rewritedetection database 75.

“Random Seed” in the rewrite detection database 75 denotes a random seedto be generated by the rewrite detection device 5, and is a 4-digithexadecimal numerical value in this embodiment. In the illustratedexample, 65,536 different values from 0000h to FFFFh are set for each“ECU Class” as “Random Seed” in the rewrite detection database 75.“Expectation” in the rewrite detection database 75 is a hash value to becalculated for “Random Seed” by the ECU 2, and is a 4-digit hexadecimalnumerical value in this embodiment. “Expectation” is stored aftercalculating a hash value using corresponding “Random Seed” for thestorage content (program, data and dummy data) of the storage unit 22 ofthe ECU 2. It is to be noted that the illustrated “Expectations” areexamples.

The rewrite detection device 5 specifies a vehicle model, an ECU classand a random seed, and makes an inquiry for an expectation to the serverdevice 7. In response to the inquiry, the server device 7 reads out acorresponding expectation from the rewrite detection database 75, andtransmits the expectation to the rewrite detection device 5.

FIG. 7 is a schematic diagram for illustrating Second ConfigurationExample of the rewrite detection database 75. In the rewrite detectiondatabase 75 of Second Configuration Example, “Vehicle Model”, “ECUClass” and “Storage Content” are stored in association with each other.“Vehicle Model” and “ECU Class” thereamong are the same as those ofFirst Configuration Example. “Storage Content” in the rewrite detectiondatabase 75 is a copy of the storage content of the storage unit 22 ofthe corresponding ECU 2.

As in the case of First Configuration Example, the rewrite detectiondevice 5 specifies a vehicle model, an ECU class and a random seed, andmakes an inquiry for an expectation to the server device 7. The serverdevice 7 reads out the storage content corresponding to the vehiclemodel and the ECU class related to the inquiry. The server device 7calculates a hash value on the basis of a random seed related to theinquiry and the read-out storage content, and transmits the calculatedhash value to the rewrite detection device 5 as an expectation.Accordingly, the server device 7 stores the same hash function as thatto be used by the hash value calculation unit 24 of the ECU 2.

In this embodiment, it is to be noted that programs and data stored inthe storage unit 22 of the ECU 2 are deemed to be identical when theprograms and data correspond to the same vehicle model and the same ECUclass. Here, depending on a difference in the destination of the vehicle1, the version of a program or the like, programs and data stored in thestorage unit 22 can be deemed to be different from each other even whenthe programs and data correspond to the same vehicle model and the sameECU class. In such a case, an item such as the version of a program isprovided in the rewrite detection database 75, for example, and a randomseed and an expectation are stored for each version, or alternativelythe storage content of the storage unit 22 is stored for each version.The rewrite detection device 5 acquires the version of a program of anECU 2 to be the object of rewrite detection processing from the ECU 2,and transmits program version information together with information suchas the random seed and the vehicle model in the process of making aninquiry for an expectation to the server device 7. The server device 7can acquire or calculate an expectation from the rewrite detectiondatabase 75 on the basis of random seed information, vehicle modelinformation, ECU class information, program version information and thelike from the rewrite detection device 5, and transmit the expectationto the rewrite detection device 5.

<Hash Value Calculation Method>

The hash value calculation unit 24 of each ECU 2 can be configured tocalculate a hash value utilizing a known hash function such as MD(Message Digest) 4, MD 5, SHA-1, SHA-256, SHA-384, SHA-512, EIPEMD-160or SHA-3. These are so-called one-way hash functions, which respectivelyoutput one hash value for inputted information. Information to beinputted into a hash function is a part or the whole of programs or datastored in the storage unit 22 of the ECU 2 in this embodiment. The hashfunction can treat what has been inputted simply as binary informationand calculate a hash value, whether any one of a program and data isinputted into the hash function or both of a program and data areinputted into the hash function. The hash value calculation unit 24stores a preset hash function, and calculates a hash value using thehash function.

The following description will give a brief explanation on a case wherethe hash value calculation unit 24 calculates a hash value using a hashfunction of SHA-1. It is to be noted that explanation on detailedprocessing of the hash function of SHA-1 and on a case where the hashvalue calculation unit 24 uses another hash function will be omitted,since these hash functions are known techniques.

In a case where the hash function of SHA-1 is utilized, the hash valuecalculation unit 24 first performs padding. In padding, the hash valuecalculation unit 24 adjusts the size of information, which is to beprocessed, to be an integer multiple of a predetermined value (512 bit)by adding excess data behind inputted information. The hash valuecalculation unit 24 then divides the padded information into blocks foreach 512 bit, and performs First Processing of calculating 80 values foreach block.

The hash value calculation unit 24 then performs Second Processing ofperforming arithmetic operation using a value calculated by FirstProcessing for an initial value having a predetermined size (160 bit)and obtaining a 160-bit value by the arithmetic operation as a hashvalue. In Second Processing, the hash value calculating unit 24 firstperforms arithmetic operation in 80 steps for the 160-bit initial value,using 80 values calculated for one block. As a result of the arithmeticoperation in 80 steps, block information can be mixed into the 160-bitinitial values, and a 160-bit value can be obtained as output. The hashvalue calculation unit 24 similarly performs arithmetic operation in 80steps for the obtained 160-bit value as an initial value, using 80values calculated for the next block. The hash value calculation unit 24performs similar processing in 80 steps for all blocks, and finallyobtains a 160-bit value as a hash value.

Moreover, in this embodiment, the hash value calculation unit 24 needsto calculate a hash value utilizing a random seed given from the rewritedetection device 5. For example, the hash value calculation unit 24 canuse a random seed as data to be added to inputted information in theabove padding. Moreover, for example, the hash value calculation unit 24can use a random seed as a 160-bit initial value in Second Processingdescribed above. In this embodiment, a random seed is used as an initialvalue of Second Processing.

It is to be noted that the way the hash value calculation unit 24utilizes a random seed is not limited to what has been described above.For example, the hash value calculation unit 24 can utilize a logicaloperation value (e.g., exclusive OR) based on a random seed andinformation in the storage unit 22 to be the object of hash valuecalculation as information to be inputted into the hash function.Moreover, for example, the hash value calculation unit 24 can use whatis obtained by adding a random seed at a predetermined position such asa head position or a tail position of information in the storage unit 22to be the object of hash value calculation as information to be inputtedinto the hash function.

<Rewrite Detection Processing>

In the process of safety inspection, periodic inspection, repair or thelike of the vehicle 1, for example, a worker at a dealer shop, a repairshop or the like connects the communication cable 6 of the rewritedetection device 5 with the connector 4 of the vehicle 1, so as toconnect the rewrite detection device 5 with the in-vehicle network 3 ofthe vehicle 1. The worker operates the operation unit 53 of the rewritedetection device 5 so as to give an instruction to start detectionprocessing of unauthorized rewrite to an ECU 2 of the vehicle 1 to therewrite detection device 5.

When the operation unit 53 accepts an instruction to start unauthorizedrewrite detection processing, the rewrite detection device 5 startscommunication with the ECU 2 of the vehicle 1 at the wired communicationunit 55. The rewrite detection device 5 in this embodiment arbitrarilyselects one of a plurality of ECUs 2 mounted on the vehicle 1, andperforms detection processing of unauthorized rewrite to a program anddata stored in the storage unit 22 of the selected ECU 2. Afterfinishing the detection processing for one ECU 2, the rewrite detectiondevice 5 performs detection processing for an unprocessed ECU 2. Therewrite detection device 5 sequentially performs detection processingfor a plurality of ECUs 2 by repeatedly performing the above processing,so as to perform unauthorized rewrite detection processing for all ECUs2, which are mounted on the vehicle 1 and can be the object ofdetection.

It is to be noted that the rewrite detection device 5 can be configuredto perform unauthorized rewrite detection processing simultaneously fora plurality of ECUs 2 connected with the in-vehicle network 3. Here, inthis embodiment, the rewrite detection device 5 performs unauthorizedrewrite detection processing sequentially for a plurality of ECUs 2 asdescribed above. Moreover, the following description will explain a casewhere the rewrite detection 5 performs unauthorized rewrite detectionprocessing for one ECU 2, in order to simplify the explanation. Similarprocessing may be repeatedly performed for a plurality of ECUs 2.

FIG. 8 is a schematic diagram for explaining rewrite detectionprocessing to be performed by the rewrite detection device 5. Therewrite detection device 5 connected with the in-vehicle network 3 ofthe vehicle 1 gives notice of a start of rewrite detection processing orthe like to an ECU 2, which is to be the object of rewrite detectionprocessing. In response, the object ECU 2 suspends other processing, forexample, so as to prepare for processing to be performed by the hashvalue calculation unit 24 (here, the other processing is not necessarilysuspended but the hash value calculation unit 24 may be configured toperform processing in parallel with the other processing).

The rewrite detection device 5 generates a random value on the basis ofan arbitrary random-number generation algorithm, and transmits the valueto the ECU 2 as a random seed. The random seed may be a random valuehaving 64 or more bits, for example. When the hash value calculationunit 24 uses SHA-1 as a hash function, the random seed can be 160-bit,for example. When receiving a random seed from the rewrite detectiondevice 5, the ECU 2 calculates a hash value using a preset hash functionon the basis of the received random seed and the storage content of thestorage unit 22. The ECU 2 transmits the calculated hash value to therewrite detection device 5.

Moreover, the rewrite detection device 5 transmits the generated randomseed to the server device 7, and makes an inquiry for an expectation ofa hash value for the random seed. At this time, the rewrite detectiondevice 5 transmits vehicle information such as a vehicle ID (IDentifier)or the vehicle model of the vehicle 1, for which rewrite detectionprocessing is performed, and ECU identification information such as anID to be used for identifying an ECU 2 to be processed, to the serverdevice 7 together with the random seed. When receiving theseinformation, the server device 7 refers to the rewrite detectiondatabase 75 of the storage unit 72. The server device 7 acquires anexpectation, for which an inquiry has been made, corresponding to therandom seed, the vehicle model and the ECU class from the rewritedetection database 75, and transmits the acquired expectation to therewrite detection device 5.

The rewrite detection device 5 compares the hash value received from theECU 2 with the expectation received from the server device 7. When thehash value and the expectation coincide with each other, the rewritedetection device 5 determines that unauthorized rewrite to a program anddata stored in the storage unit 22 of the ECU 2 has not been performed.On the other hand, when the hash value and the expectation do notcoincide with each other, the rewrite detection device 5 determines thatunauthorized rewrite to a program and data in the ECU 2 has beenperformed. The rewrite detection device 5 displays whether unauthorizedprocessing has been performed or not at the display unit 54 as theresult of rewrite detection processing.

The rewrite detection device 5 also measures a period of time fromtransmission of a random seed to the ECU 2 to reception of a hash value.The rewrite detection device 5 determines whether the measured period oftime exceeds a threshold or not, and, when the measured period of timeexceeds the threshold, determines that unauthorized rewrite to a programand data in the ECU 2 has been performed. It is to be noted that thethreshold to be used for the determination is preliminarily decided inthe design phase or the like of this system in consideration of thecommunication speed of the rewrite detection device 5 and the ECU 2, thethroughput of the ECU 2, and the like.

FIG. 9 is a flowchart for illustrating the process procedures of rewritedetection processing to be performed by the rewrite detection device 5.The processing unit 51 of the rewrite detection device 5 generates arandom seed on the basis of the random-number generation algorithm (stepS1). The processing unit 51 transmits the generated random seed from thewired communication unit 55 to an ECU 2 to be processed (step S2). Theprocessing unit 51 starts time measuring utilizing an inner timer or thelike (step S3).

The processing unit 51 determines whether a hash value transmitted fromthe ECU 2 to be processed for the random seed has been received at thewired communication unit 55 or not (step S4), and, when a hash value hasnot been received (S4: NO), waits until a hash value is received. When ahash value is received (S4: YES), the processing unit 51 determineswhether a measured period of time from transmission of the random seedto reception of the hash value exceeds a predetermined threshold or not(step S5). When the measured period of time exceeds the threshold (S5:YES), the processing unit 51 determines that unauthorized rewrite hasbeen performed (step S10), displays notice thereof at the display unit54, and terminates the processing.

When the measured period of time does not exceed the threshold (S5: NO),the processing unit 51 transmits a random seed, vehicle information andECU identification information from the wireless communication unit 56to the server device 7, and makes an inquiry for an expectation (stepS6). The processing unit 51 determines whether an expectationtransmitted from the server device 7 has been received for the inquiryor not (step S7), and, when an expectation has not been received (S7:NO), waits until an expectation is received.

When receiving an expectation from the server device 7 (S7: YES), theprocessing unit 51 determines whether the hash value received in step S4and the expectation received in step S7 coincide with each other or not(step S8). When the hash value and the expectation coincide with eachother (S8: YES), the processing unit 51 determines that unauthorizedrewrite has not been performed (step S9), displays notice thereof at thedisplay unit 54, and terminates the processing. When the hash value andthe expectation do not coincide with each other (S8: NO), the processingunit 51 determines that unauthorized rewrite has been performed (stepS10), displays notice thereof at the display unit 54, and terminates theprocessing.

FIG. 10 is a flowchart for illustrating the process procedures ofrewrite detection processing to be performed by an ECU 2. The processingunit 21 of the ECU 2 determines whether a random seed transmitted fromthe rewrite detection device 5 has been received at the communicationunit 23 or not (step S21), and, when a random seed has not been received(S21: NO), waits until a random seed is received. When a random seed isreceived (S21: YES), the hash value calculation unit 24 of theprocessing unit 21 calculates a hash value using a predetermined hashfunction on the basis of the random seed from the rewrite detectiondevice 5 and the storage content of the storage unit 22 (step S22). Theprocessing unit 21 transmits the hash value, which has been calculatedby the hash value calculation unit 24, from the communication unit 23 tothe rewrite detection device 5 (step S23), and terminates theprocessing.

FIG. 11 is a flowchart for illustrating the process procedures ofrewrite detection processing to be performed by the server device 7. Theprocessing unit 71 of the server device 7 determines whether an inquiryfor an expectation from the rewrite detection device 5 has been receivedat the communication unit 73 or not (step S31), and, when an inquiry hasnot been received (S31: NO), waits until an inquiry is received. When aninquiry from the rewrite detection device 5 is received (S31: YES), theprocessing unit 71 acquires an expectation from the rewrite detectiondatabase 75 of the storage unit 72 on the basis of a random seed,vehicle information, ECU identification information and the likeincluded in the inquiry (step S32). The processing unit 71 transmits theacquired expectation from the communication unit 73 to the rewritedetection device 5 (step S33), and terminates the processing.

<Conclusion>

In the rewrite detection system according to Embodiment 1 having theabove configuration, the rewrite detection device 5 generates a randomseed and transmits the random seed to an ECU 2, and the ECU 2 calculatesa hash value using a predetermined hash function on the basis of thereceived random seed and the storage content (program or data) of thestorage unit 52 and transmits the hash value to the rewrite detectiondevice 5. The rewrite detection device 5 determines whether the hashvalue received from the ECU 2 is valid or not, and determines whetherunauthorized rewrite to a program or data has been performed or not.That is, the rewrite detection device 5 can determine that unauthorizedrewrite has not been performed when the hash value is valid, or candetermine that unauthorized rewrite has been performed when the hashvalue is invalid.

This allows the rewrite detection device 5 to detect unauthorizedrewrite to a program or data in the ECU 2, and makes it possible toappropriately carry out treatment such as operation stop, repair orreplacement of the ECU 2 for which unauthorized rewrite has beenperformed. Since added to the ECU 2 is only a function to calculate ahash value, it is possible to suppress a cost increase of the ECU 2 forimplementing the system. This system can be implemented more easily andat a lower cost than a case where a function to prevent unauthorizedrewrite is mounted.

Moreover, in the storage unit 22 of the ECU 2, dummy data having arandom value is stored in a surplus area of a case where an authorizedprogram and authorized data are stored. Although unauthorized processingmay possibly be performed by compressing an authorized program orauthorized data stored in the storage unit 22 and storing anunauthorized program or unauthorized data in an unused area of thestorage unit 22 obtained by the compression, for example, it is possibleto make it difficult to compress a program or data by prestoring dummydata in a surplus area. It is to be noted that a configuration wherein aprogram or data is stored in the storage unit 22 so that surplus areaslie scattered and dummy data lies scattered at a plurality of locationsin the storage unit 22 makes it difficult to perform unauthorizedprocessing.

Moreover, the rewrite detection device 5 measures a period of time fromtransmission of a random seed to an ECU 2 to reception of a hash value,and, when the measured period of time exceeds a preset threshold,determines that unauthorized rewrite has been (or may have been)performed. As a result, when unauthorized processing such as compressingand utilizing a program, data or the like in the ECU 2, for example, isperformed and a longer period of time is required before transmission ofa hash value than a normal state, this can be detected.

Moreover, the server device 7 transmits an expectation in response to aninquiry from the rewrite detection device 5, and the rewrite detectiondevice 5 detects rewrite in accordance with whether the expectationreceived from the server device 7 and the hash value received from theECU 2 coincide with each other or not. Although an expectation in therewrite detection device 5 may possibly be rewritten in an unauthorizedmanner in a case where the rewrite detection device 5 is configured tostore an expectation of a hash value, for example, a configurationwherein an expectation is acquired from the server device 7 preventssuch unauthorized rewrite to an expectation.

Moreover, the rewrite detection device 5 is configured to be attachableto and detachable from the connector 4 of the in-vehicle network 3 ofthe vehicle 1 via the communication cable 6. Such a rewrite detectiondevice 5 may be provided in a dealer shop, a maintenance factory or thelike of the vehicle 1, for example, so that unauthorized rewrite to aprogram or data in the ECU 2 can be detected in the process of safetyinspection, periodic inspection, repair or the like of the vehicle 1.Moreover, for example, in the case of a vehicle 1 for car rental, carsharing or the like, the rewrite detection device 5 can performunauthorized rewrite detection after the vehicle is returned.

Although this embodiment has a configuration wherein communicationbetween the rewrite detection device 5 and the vehicle 1 is made bywired communication via the communication cable 6, it is to be notedthat this is not restrictive and the rewrite detection device 5 and thevehicle 1 may be configured to make wireless communication such as awireless LAN. Moreover, although the rewrite detection device 5 isconfigured to communicate with the server device 7 at the wirelesscommunication unit 56, this is not restrictive and the rewrite detectiondevice 5 may be configured to communicate with the server device 7 bywired communication. Moreover, although the rewrite detection device 5is configured to be connected with the connector 4 of the in-vehiclenetwork 3 of the vehicle 1, this is not restrictive and the rewritedetection device 5 may be configured to be connected with a device suchas a gateway mounted on the vehicle 1, for example, and communicate withan ECU 2 connected with the in-vehicle network 3 via the gateway.

Moreover, although the rewrite detection device 5 is configured toacquire an expectation from the server device 7 after acquiring a hashvalue from the ECU 2, this is not restrictive and the rewrite detectiondevice 5 may acquire a hash value after acquiring an expectation or mayacquire a hash value and an expectation in parallel. Moreover, althoughthe rewrite detection device 5 is configured to detect unauthorizedrewrite for a plurality of ECUs 2 mounted on the vehicle 1 one by one insequence, this is not restrictive. The rewrite detection device 5 maysimultaneously transmit a random seed to a plurality of ECUs 2 bybroadcasting, for example, acquire hash values from the plurality ofECUs 2, and perform rewrite detection processing for the plurality ofECUs 2 at the same time.

Moreover, the rewrite detection database 75 may be provided not in theserver device 7 but in the rewrite detection device 5. That is, therewrite detection system may not be provided with the server device 7,and the rewrite detection device 5 may be configured to store orcalculate an expectation for a hash value. Moreover, although thisembodiment has been explained using an example of a rewrite detectionsystem for detecting rewrite to a program or data in an ECU 2 mounted onthe vehicle 1, this is not restrictive and a rewrite detection systemmay be configured to detect rewrite to a program or data in aninformation processing device, which is mounted on another mobile bodysuch as an airplane or a ship, for example.

(Variation)

Although the rewrite detection system according to Embodiment 1described above has a configuration wherein the rewrite detection device5 generates a random seed, this is not restrictive. For example, theserver device 7 may be configured to generate a random seed. In such aconfiguration, the rewrite detection device 5 makes an inquiry fortransmission of a random seed and an expectation to the server device 7.In response to the inquiry, the server device 7 creates a random seed,acquires or calculates a corresponding expectation on the basis of therewrite detection database 75, and transmits the random seed and theexpectation to the rewrite detection device 5. The rewrite detectiondevice 5 transmits a random seed, which has been received from theserver device 7, to an ECU 2, receives a hash value, which has beencalculated on the basis of the random seed, from the ECU 2, and comparesthe expectation from the server device 7 with the hash value from theECU 2 so as to detect unauthorized rewrite.

Embodiment 2

In the rewrite detection system according to Embodiment 1 describedabove, the whole of the storage unit 22 of the ECU 2 is to be the objectof hash value calculation by the hash value calculation unit 24. Whenthe storage unit 22 of the ECU 2 has large storage capacity and theprocessing unit 21 has low throughput, for example, hash valuecalculation may possibly require a long period of time. Therefore, as arewrite detection system according to Embodiment 2, a method ofaccelerating hash value calculation by an ECU 2 will be described below.

In the rewrite detection system according to Embodiment 2, the rewritedetection device 5 can specify a storage area in the storage unit 22 tobe the object of hash value calculation by the hash value calculationunit 24 of an ECU 2. The rewrite detection device 5 can specify astorage area in a manner as “from address X to address Y at addressinterval Z” or “Y bytes from address X at address interval Z”, forexample. The rewrite detection device 5 transmits the above values X, Yand Z as storage area specification information to the ECU 2 togetherwith a random seed. It is to be noted that the values X, Y and Z may bepreset or may be randomly decided each time.

It is to be noted that a method of specifying a storage area is notlimited to the above example. For example, a method of specifying onecontinuous area in a manner such as “from address X to address Y” may beemployed. Moreover, for example, a method of specifying a plurality ofdiscontinuous areas by not specifying the head position and the tailposition but specifying only the interval between storage areas in amanner such as “at address interval Z” may be employed. Moreover, forexample, a method of specifying a plurality of discontinuous areas byspecifying a plurality of head positions and tail positions in a mannersuch as “from address X1 to address Y1, from address X2 to address Y2, .. . , from address Xn to address Yn” may be employed.

The rewrite detection device 5 may acquire a hash value corresponding toa part of the storage unit 22 of the ECU 2 as described above one time,so as to detect rewrite on the basis of one hash value. Alternatively,the rewrite detection device 5 may acquire a hash value a plurality oftimes while changing a specified storage area, so as to detect rewriteon the basis of a plurality of hash values. It is to be noted that therewrite detection device 5 preferably acquires a hash value a pluralityof times by specifying a storage area to cover the whole storage area ofthe storage unit 22.

When storage area specification information from the rewrite detectiondevice 5 is given, the ECU 2 reads out data from a specified storagearea, and the hash value calculation unit 24 calculates a hash value onthe basis of the read-out data and the random seed from the rewritedetection device 5. The ECU 2 transmits the calculated hash value to therewrite detection device 5.

Here, when specification of a storage area by the storage areaspecification information from the rewrite detection device 5 does notsatisfy a predetermined condition, the ECU 2 does not calculate ortransmit a hash value. For example, the ECU 2 uses a predeterminedcondition that the storage capacity of a specified storage area is apredetermined size such as A byte or a constant multiple of apredetermined size (e.g., N×A byte), for determining whether a hashvalue is to be transmitted or not.

Moreover, after transmitting a hash value to the rewrite detectiondevice 5, the ECU 2 starts time measuring by an inner timer or the like,and does not transmit a hash value until a preset standby time elapseseven when receiving the next random seed, area specification informationand the like from the rewrite detection device 5. Since the ECU 2 setssuch a limit on transmission of a hash value, it is possible to preventabuse of the function of hash value calculation for partial data in thestorage unit 22.

In the process of making an inquiry for an expectation to the serverdevice 7, the rewrite detection device 5 also transmits storage areaspecification information (values X, Y and Z) to the server device 7together with a random seed, vehicle information, ECU identificationinformation and the like. The server device 7 acquires or calculates anappropriate expectation on the basis of these information given from thewriting detection device 5, and transmits the expectation to the rewritedetection device 5.

In a case where the rewrite detection database 75 of the server device 7is to preliminarily calculate and store an expectation as illustrated inFIG. 6, it is to be noted that the rewrite detection database 75according to Embodiment 2 needs to store an expectation for each set ofX, Y and Z which can be specified. In another case where the rewritedetection database 75 is to store the storage content of the storageunit 22 as illustrated in FIG. 7, the server device 7 according toEmbodiment 2 can utilize a similar rewrite detection database 75. Insuch a case, the server device 7 may extract a required part from thestorage content of the rewrite detection database 75 on the basis of thestorage area specification information, which has been given from therewrite detection device 5 together with the inquiry, so as to calculatea hash value.

The rewrite detection device 5 compares the hash value received from theECU 2 with the expectation received from the server device 7, and, whenthe values coincide with each other, determines that unauthorizedrewrite has not been performed, or, when the values do not coincide witheach other, determines that unauthorized rewrite has been performed.

FIG. 12 is a flowchart for illustrating the process procedures ofrewrite detection processing to be performed by an ECU 2 according toEmbodiment 2. The processing unit 21 of the ECU 2 according toEmbodiment 2 determines whether a random seed transmitted from therewrite detection device 5 has been received at the communication unit23 or not (step S41), and, when a random seed has not been received(S41: NO), waits until a random seed is received. When a random seed isreceived (S41: YES), the processing unit 21 determines whether apredetermined standby time has elapsed from transmission of the lasthash value to the rewrite detection device 5 or not (step S42). When astandby time has not elapsed (S42: NO), the processing unit 21terminates the processing.

When a predetermined standby time has elapsed from transmission of thelast hash value (S42: YES), the processing unit 21 acquires storage areaspecification information, which has been received from the rewritedetection device 5 together with a random seed (step S43), anddetermines whether specification of a storage area by the storage areaspecification information satisfies a predetermined condition or not(step S44). When specification of a storage area does not satisfy thepredetermined condition (S44: NO), the processing unit 21 terminates theprocessing. When specification of a storage area satisfies thepredetermined condition (S44: YES), the processing unit 21 reads outdata in the specified storage area (step S45).

The hash value calculation unit 24 of the processing unit 21 calculatesa hash value using a predetermined hash function on the basis of therandom seed from the rewrite detection device 5 and data in thespecified storage area (step S46). The processing unit 21 transmits ahash value, which has been calculated by the hash value calculation unit24, from the communication unit 23 to the rewrite detection device 5(step S47). The processing unit 21 then starts time measuring using aninner timer or the like (step S48) in order to determine elapse of astandby time from transmission of a hash value, and terminates theprocessing.

It is to be noted that the process procedures of the server device 7 andthe rewrite detection device 5 according to Embodiment 2 are omitted inillustration of the flowchart. The rewrite detection device 5 accordingto Embodiment 2 may transmit storage area specification information tothe ECU 2 or the server device 7 in the process of transmitting a randomseed to the ECU 2 in step S2 of the flowchart illustrated in FIG. 9, orin the process of making an inquiry for an expectation to the serverdevice 7 in step S6. Moreover, the server device 7 according toEmbodiment 2 may acquire an expectation in consideration of storage areaspecification information from the rewrite detection device 5 in theprocess of acquiring an expectation from the rewrite detection databasein step S32 illustrated in FIG. 11.

In the rewrite detection system according to Embodiment 2 having theabove configuration, the rewrite detection device 5 transmits storagearea specification information, which specifies an area in the storageunit 22 to be the object of hash value calculation, together in theprocess of transmitting a random seed to the ECU 2. The ECU 2 calculatesa hash value on the basis of a program or data stored in a storage areaspecified by the storage area specification information. This shortens aperiod of time required for hash value calculation processing by the ECU2. It is to be noted that the rewrite detection device 5 may acquire ahash value a plurality of times from the ECU 2 so as to determinewhether unauthorized rewrite has been performed or not, while changingthe object area of hash value calculation.

Moreover, the storage area specification information may includeinformation, which specifies the head position and the tail position ofa storage area, or information, which specifies the head position andthe size of the storage area. Moreover, a plurality of discontinuousareas may be specified as a storage area to be the object of hash valuecalculation, or the storage area specification information may beinformation which specifies the interval between a plurality of areas,for example. The rewrite detection device 5 can combine theseinformation so as to specify a storage area in a manner such as “fromaddress X to address Y at address interval Z”, for example.

After calculating a hash value on the basis of a random seed andtransmitting the hash value to the rewrite detection device 5, the ECU 2does not transmit a hash value until a predetermined period of timeelapses even when the next random seed is given from the rewritedetection device 5. This can limit the amount of hash values to beobtained in a certain period of time, and therefore makes it difficultto get a hash value in an unauthorized manner so as to decode a programor data.

Although Embodiment 2 has a configuration wherein the rewrite detectiondevice 5 generates storage area specification information and transmitsthe storage area specification information to the ECU 2 and the serverdevice 7, it is to be noted that this is not restrictive. For example,the ECU 2 and the server device 7 may be configured to store anarithmetic expression to be used for calculating the head position, thetail position, the interval and the like of storage areas on the basisof a random seed, so as to decide the head position, the tail position,the interval and the like of storage areas by receiving a random seedfrom the rewrite detection device 5 and performing an arithmeticoperation using the arithmetic expression. In the case of such aconfiguration, a random seed may be used only for deciding a storagearea and not be directly involved in hash value calculation.

Since the other configuration of the rewrite detection system accordingto Embodiment 2 is similar to the configuration of the rewrite detectionsystem according to Embodiment 1, like codes are attached to similarcomponents, and detailed explanation thereof will be omitted.

Embodiment 3

Although the rewrite detection systems according to Embodiments 1 and 2described above have configurations wherein the rewrite detection device5 is attachable to and detachable from the in-vehicle network 3 of thevehicle 1, this is not restrictive. In Embodiment 3, a configurationwherein the rewrite detection device 5 is mounted on the vehicle 1 willbe explained.

FIG. 13 is a schematic diagram for illustrating the configuration of arewrite detection system according to Embodiment 3. The rewritedetection system according to Embodiment 3 has a configuration wherein afunction to perform rewrite detection processing is provided in agateway 305 mounted on the vehicle 1. The gateway 305 is connected witha plurality of communication lines which compose the in-vehicle network3 of the vehicle 1, and performs processing to relay informationtransmission and reception between these communication lines. Moreover,the gateway 305 has a wireless communication function, and cancommunicate with the server device 7 utilizing the wirelesscommunication function via the network 9 such as the Internet. Here, thegateway 305 may not have a wireless communication function, and thegateway 305 may be configured to communicate with the server device 7utilizing a wireless communicator mounted on the vehicle 1.

FIG. 14 is a block diagram for illustrating the configuration of thegateway 305. The gateway 305 according to Embodiment 3 is composed of aprocessing unit 51, a storage unit 52, wired communication units 55, awireless communication unit 56 and the like. The processing unit 51 isconstituted of an arithmetic processing unit such as a CPU, and performsprocessing to relay transmission and reception of information betweencommunication lines and also performs rewrite detection processingsimilar to that of the rewrite detection devices 5 of Embodiments 1 and2. The storage unit 52 is constituted of a memory element such as aflash memory, and stores a program to be executed by the processing unit51, data to be used for the execution, and the like. Moreover, inEmbodiment 3, the storage unit 52 of the gateway 305 stores expectationbackup information.

Moreover, the gateway 305 has a plurality of wired communication units55, and each wired communication unit 55 is connected with acommunication line of the in-vehicle network 3. The processing unit 51acquires information received at one wired communication unit 55, andrelays information by giving the information to the other wiredcommunication units 55 so as to cause the same to transmit theinformation. The wireless communication unit 56 is to make wirelesscommunication utilizing a wireless LAN, a portable telephone network orthe like. Here, depending on the peripheral environment or the like ofthe vehicle 1, the gateway 305 cannot always make wireless communicationusing the wireless communication unit 56.

The gateway 305 performs rewrite detection processing in preset andpredetermined timing such as when the ignition switch of the vehicle 1is turned on, for example. When it is determined in rewrite detectionprocessing that unauthorized rewrite to a program or data in the ECU 2has been performed, the gateway 305 displays a warning message or thelike at a display unit (illustration is omitted) provided near thedriver seat of the vehicle 1. Moreover, the gateway 305 may performprocessing such as prohibition of traveling of the vehicle 1 whenunauthorized rewrite is performed.

Moreover, wireless communication of the wireless communication unit 56with the server device 7 cannot always be made as described above.Therefore, the gateway 305 stores information related to an expectation,which has been acquired from the server device 7 while wirelesscommunication can be made, in the storage unit 52 as expectation backupinformation. When communication with the server device 7 cannot be madein the process of rewrite detection processing, the gateway 305determines whether a hash value obtained from the ECU 2 is valid or noton the basis of the expectation backup information stored in the storageunit 52.

FIG. 15 is a flowchart for illustrating the process procedures ofrewrite detection processing to be performed by the gateway 305according to Embodiment 3. In predetermined timing such as when theignition switch of the vehicle 1 is turned on, for example, theprocessing unit 51 of the gateway 305 generates a random seed on thebasis of a random-number generation algorithm (step S51), and transmitsthe generated random seed to an ECU 2 to be processed (step S52). Theprocessing unit 51 determines whether a hash value transmitted from theECU 2 to be proceed for the random seed has been received at the wiredcommunication unit 55 or not (step S53), and, when a hash value has notbeen received (S53: NO), waits until a hash value is received. When ahash value is received (S53: YES), the processing unit 51 determineswhether communication of the wireless communication unit 56 with theserver device 7 can be made or not (step S54).

When wireless communication can be made (S54: YES), the processing unit51 makes an inquiry for an expectation to the server device 7 at thewireless communication unit 56 (step S55). It is to be noted that, whenreceiving an inquiry for an expectation from the gateway 305, the serverdevice 7 does not transmit one expectation corresponding to one randomseed to the gateway 305 but extracts all expectations related to theobject ECU 2 of the vehicle 1 from the rewrite detection database 75 andtransmits the expectations to the gateway 305 in Embodiment 3. Theprocessing unit 51 of the gateway 305 determines whether expectationstransmitted from the server device 7 in response to the inquiry havebeen received or not (step S56), and, when expectations have not beenreceived (S56: NO), waits until expectations are received. Whenexpectations from the server device 7 are received (S56: YES), theprocessing unit 51 stores all received expectations in the storage unit52 as expectation backup information (step S57), extracts what isrequired from all received expectations, and proceeds the processing tostep S59. When wireless communication cannot be made (S54: NO), theprocessing unit 51 reads out a required expectation from the expectationbackup information in the storage unit 52 (step S58), and proceeds theprocessing to step S59.

The processing unit 51 compares the hash value received from the ECU 2with the expectation received from the server device 7 or theexpectation read out from the storage unit 52, and determines whetherthe hash value and the expectation coincide with each other or not (stepS59). When the hash value and the expectation coincide with each other(S59: YES), the processing unit 51 determines that unauthorized rewritehas not been performed (step S60), displays notice thereof at thedisplay unit 54, and terminates the processing. When the hash value andthe expectation do not coincide with each other (S59: NO), theprocessing unit 51 determines that unauthorized rewrite has beenperformed (step S61), displays notice thereof at the display unit 54,and terminates the processing.

In the rewrite detection system according to Embodiment 3 having theabove configuration, the gateway 305 having a function similar to thatof the rewrite detection device 5 is mounted on the vehicle 1, andperforms processing to detect unauthorized rewrite to a program or datain an ECU 2. This makes it easy to increase the frequency of detectionprocessing by, for example, detecting unauthorized rewrite each time theengine of the vehicle 1 starts.

Moreover, when communication with the server device 7 can be made, thegateway 305 acquires expectations and stores expectations in the storageunit 52 as expectation backup information. When communication with theserver device 7 cannot be made in the process of detection processing,the gateway 305 performs detection processing on the basis of the storedexpectation backup information. This allows the gateway 305 to performdetection processing even when communication with the server device 7cannot be made.

Although Embodiment 3 has a configuration wherein the gateway 305mounted on the vehicle 1 detects unauthorized rewrite to a program ordata in an ECU 2, this is not restrictive. For example, a car navigationdevice mounted on the vehicle 1, any one ECU 2 or the like may beconfigured to perform detection processing. Moreover, although thegateway 305 is configured to store expectation backup information whenexpectations can be acquired from the server device 7 in detectionprocessing, this is not restrictive. The gateway 305 may acquireexpectations from the server device 7 and store expectations asexpectation backup information in various other timing. Moreover, thegateway 305 may be configured to perform detection processing whencommunication with the server device 7 can be made, and not to performdetection processing when communication cannot be made.

Since the other configuration of the rewrite detection system accordingto Embodiment 3 is similar to the configuration of the rewrite detectionsystem according to Embodiment 1, like codes are attached to similarcomponents, and detailed explanation thereof will be omitted.

REFERENCE SIGNS LIST

-   -   1 Vehicle (Mobile Body)    -   2 ECU (Information Processing Device)    -   3 In-Vehicle Network (Network)    -   4 Connector    -   5 Rewrite Detection Device    -   6 Communication Cable    -   7 Server Device    -   9 Network    -   21 Processing Unit    -   22 Storage Unit    -   23 Communication Unit    -   24 Hash Value Calculation Unit (Hash Value Calculation Means)    -   51 Processing Unit (Seed Information Transmission Means, Hash        Value Reception Means, Hash Value Determination Means,        Measurement Means, Inquiry Means, Reception Means)    -   52 Storage Unit    -   53 Operation Unit    -   54 Display Unit    -   55 Wired Communication Unit    -   56 Wireless Communication Unit    -   71 Processing Unit    -   72 Storage Unit    -   73 Communication Unit    -   75 Rewrite Detection Database

1.-19. (canceled)
 20. A rewrite detection system for checking aninformation processing device, which has a storage unit for storing aprogram or data, a processing unit for performing processing based on aprogram or data stored in the storage unit, and a communication unit forcommunicating with another device via a network, so as to detect rewriteto a program or data stored in the storage unit, comprising a rewritedetection device, which has: seed information transmission unit fortransmitting seed information to the information processing device viathe network; hash value reception unit for receiving a hash valuetransmitted from the information processing device in response to seedinformation transmitted by the seed information transmission unit; andhash value determination unit for determining whether a hash valuereceived by the hash value reception unit is valid or not, and detectsrewrite in accordance with a result of determination by the hash valuedetermination unit, wherein the information processing device has hashvalue calculation unit for calculating a hash value based on seedinformation transmitted by the seed information transmission unit and aprogram or data stored in the storage unit, and is configured totransmit a hash value calculated by the hash value calculation unit tothe rewrite detection device.
 21. The rewrite detection system accordingto claim 20, wherein the seed information transmission unit of therewrite detection device transmits storage area specificationinformation, which specifies a storage area in the storage unit, to theinformation processing device together with the seed information, andthe hash value calculation unit of the information processing device isconfigured to calculate a hash value on the basis of the seedinformation and a program or data stored in a storage area in thestorage unit, which is specified by the storage area specificationinformation transmitted together with the seed information.
 22. Therewrite detection system according to claim 21, wherein the seedinformation transmission unit is configured to transmit the storage areaspecification information including information which specifies a headposition of a storage area, and a tail position or a size of the storagearea.
 23. The rewrite detection system according to claim 21, wherein aplurality of discontinuous areas can be specified as the storage area,and the seed information transmission unit is configured to transmit thestorage area specification information including information whichspecifies the plurality of areas.
 24. The rewrite detection systemaccording to claim 23, wherein the storage area specificationinformation is information which specifies an interval between theplurality of areas.
 25. The rewrite detection system according to claim21, wherein the information processing device is configured not totransmit a hash value to the rewrite detection device if specificationof a storage area by the storage area specification information receivedtogether with the seed information does not satisfy a predeterminedcondition.
 26. The rewrite detection system according to claim 25,wherein the information processing device is configured not to transmita hash value to the rewrite detection device if a size of a storage areaspecified by the storage area specification information is neither apredetermined size nor a size of a constant multiple of thepredetermined size.
 27. The rewrite detection system according to claim20, wherein the information processing device decides a storage area inthe storage unit to be an object of hash value calculation on the basisof seed information transmitted by the seed information transmissionunit, and the hash value calculation unit is configured to calculate ahash value on the basis of a program or data stored in the storage areadecided on the basis of seed information.
 28. The rewrite detectionsystem according to claim 20, wherein the information processing deviceis configured not to transmit a hash value until a predetermined periodof time elapses after transmitting a hash value to the rewrite detectiondevice.
 29. The rewrite detection system according to claim 20, whereinthe storage unit stores random data in a surplus area other than astorage area where the program or data is stored.
 30. The rewritedetection system according to claim 20, wherein the rewrite detectiondevice has measurement unit for measuring a period of time fromtransmission of seed information by the seed information transmissionunit to reception of a hash value by the hash value reception unit, andis configured to detect rewrite in accordance with a period of timemeasured by the measurement unit.
 31. The rewrite detection systemaccording to claim 20, wherein the seed information transmission unit isconfigured to transmit a random value as the seed information.
 32. Therewrite detection system according to claim 20, further comprising aserver device having transmission unit for transmitting an expectationof the hash value for the seed information, wherein the rewritedetection device has: inquiry unit for making an inquiry for anexpectation of the hash value for the seed information to the serverdevice; and reception unit for receiving the expectation transmittedfrom the server device for the inquiry from the inquiry unit, and thehash value determination unit is configured to determine whether a hashvalue received by the hash value reception unit is valid or not on thebasis of an expectation received by the reception unit.
 33. The rewritedetection system according to claim 20, further comprising a serverdevice having transmission unit for transmitting the seed informationand the expectation of the hash value, wherein the rewrite detectiondevice has: inquiry unit for making an inquiry for the seed informationand the expectation to the server device; and reception unit forreceiving the seed information and the expectation transmitted from theserver device for the inquiry from the inquiry unit, the seedinformation transmission unit is configured to transmit the seedinformation, which has been received by the reception unit from theserver device, to the information processing device, and the hash valuedetermination unit is configured to determine whether a hash valuereceived by the hash value reception unit is valid or not on the basisof an expectation received by the reception unit.
 34. The rewritedetection system according to claim 32, wherein the rewrite detectiondevice is mounted on a mobile body, and, when communication with theserver device can be made, causes the inquiry unit to make an inquiry,causes the reception unit to receive the expectation, and stores thereceived expectation, and the hash value determination unit isconfigured to determine whether a hash value received by the hash valuereception unit is valid or not on the basis of the stored expectation.35. The rewrite detection system according to claim 33, wherein therewrite detection device is mounted on a mobile body, and, whencommunication with the server device can be made, causes the inquiryunit to make an inquiry, causes the reception unit to receive theexpectation, and stores the received expectation, and the hash valuedetermination unit is configured to determine whether a hash valuereceived by the hash value reception unit is valid or not on the basisof the stored expectation.
 36. The rewrite detection system according toclaim 20, wherein the rewrite detection device is mounted on a mobilebody.
 37. The rewrite detection system according to claim 20, whereinthe rewrite detection device is configured to be attachable to anddetachable from the network.
 38. A rewrite detection device fordetecting rewrite to a program or data stored in a storage unit ofanother device, comprising: seed information transmission unit fortransmitting seed information to the another device via a network; hashvalue reception unit for receiving a hash value transmitted from theanother device in response to seed information transmitted by the seedinformation transmission unit; and hash value determination unit fordetermining whether a hash value received by the hash value receptionunit is valid or not, wherein rewrite is detected in accordance with aresult of determination by the hash value determination unit.
 39. Aninformation processing device comprising: a storage unit for storing aprogram or data; a processing unit for performing processing based on aprogram or data stored in the storage unit; a communication unit forcommunicating with another device via a network; and hash valuecalculation unit for calculating a hash value based on seed informationtransmitted from another device and a program or data stored in thestorage unit, wherein a hash value calculated by the hash valuecalculation unit is transmitted to the another device.